In the modern digital age which belongs to the fast and competitive ones time became one of the expensive things to spend with. Everyone tries to minimize the amount of time they spend for every deal. So technologies are emerging to satisfy this desire of people.This project aims at the point of developing an electronic system which helps people to control any process or devices from a remote location using a PSTN (Public Switched Telephone Network).So it has the name Device Controlling System.

The project is divided into two functional modules .The system consists of a hardware unit (consisting of a microcontroller based relay operating system and a Intel microprocessor based system Working on Microsoft windows operating system) plus a software unit which consists of Microsoft Windows GUI program which act as an interface between user and the system and also act as an interface between hardware unit and users phone.

Introduction

The project aims in developing an microcontroller based electronic relay operating system and a Microsoft Windows GUI application which act as an interface between user and system and also act as an interface between telephone system and microcontroller.

The system can be considered as a combination of hardware and software units.The microcontroller based electronic relay operating system plus the personal computer is the hardware unit. Microsoft Windows GUI application which uses the MICROSOFT TAPI functions is the software part. The users commands from the phone is handled by this TAPI functions and the program communicates with microcontroller through a serial port to alter the device status according to users desire. The application also keeps a record of the status of devices in a database and it is updated after each operation.

You can look at the GUI application as a software layer that lies between the microcontroller and telephone system. It provides user an interface to add or remove new devices to the system.

In short the system has following features:-

a).New devices can be connected to the pins provided by the MICROCONTROLLER for ....Controlling.
b).The devices can be enabled to be controlled by adding them in the device list in ....GUI application or the devices can also be disabled by removing them from the list.
c).The users who are trying to access the system will be checked for authenticity by ....the application.

Functionalities
As we said earlier the project is divided into two functional modules they are :-

1. PIC MICROCONTROLLER based electronic relay operating system
The function of this module is to alter the status of devices or processes to be controlled according to the commands from 'I API program. The programmed microcontroller communicates with TAPI program through serial port of the computer. The microcontroller considers the port data send by the TAPI program as an interrupt and executes the particular ISR(interrupt service routine).After executing the ISR the microcontroller returns the status of the devices.

2. MICROSOFT TAPI (telephonv application program interface) based telephone management system.
The function of this module is to handle the telephone call from the users. Telephony integrates computer with communications devices and networks.The TAPI program first check whether the user is authentified or not then accepts his commands. The program communicates with microcontroller to alter the device status through serial port according to users desire. The program also keeps a record of status of devices in a database which is updated on each operation.